Introduction

Have you ever been curious as to why infants and young children seem more susceptible and more affected by rotavirus, compared to teens and adults? Rotavirus is an extremely contagious virus that primarily affects the digestive system, causing both diarrhoea and nausea in individuals, often having mild effects in older children and adults but can be life-threatening for younger children. Rotaviruses, since their discovery, have been identified as the most common diarrheal disease, often requiring treatment or hospitalisation in those under 5 years old. In fact, rotavirus has been found to account for over 4.6 million diarrheal deaths in children under the age of 5.¹ To satisfy this curiosity, this article delves into how different age groups are affected by the virus, illustrating why those under the age of 5 are more vulnerable, and what this entails for their health. Therefore, if you are a parent with young children, a caretaker, or simply curious about how different age groups are affected by rotavirus, then this article will help you learn about crucial insights, symptoms, and prevention methods. 

Rotavirus infection 

As mentioned in the introduction, rotavirus is an extremely contagious gastrointestinal (GI) infection that causes inflammation in both the stomach and the intestines (gastroenteritis) leading to severe vomiting and diarrhea.² It is most commonly spread by direct person-to-person contact, primarily transmitted via the faecal-oral route.³ This occurs when an individual touches either infected stool or an object that has been in contact with it, and then ingests these germs after touching their face or mouth. 

In infants and young children

Rotavirus is known to be one of the leading causes of life-threatening gastroenteritis amongst babies and young children, causing this to be associated with substantial morbidity and mortality.⁴ Whilst infections begin during the neonatal period, they increase significantly after 3 months of age, leading to these viruses being one of the most common causes of diarrhoea in children under the age of 5, occurring particularly in those between the ages of 6 months and 2 years.^4,5 Whilst there is no one explanation as to why this is, there are a few factors that are thought to contribute towards the vulnerability of infants and younger children,⁶ including:

• Less developed immune systems: infants and young children have less developed immune systems making it more difficult for them to fight the rotavirus infection⁶
• Lack of prior immunity: children of a younger age are less likely to have previously been in contact with rotaviruses, meaning they are more susceptible to the infection
• Increased exposure: They are more likely to come into close contact with others (i.e., nursery setting), and they engage in behaviours that increase the spread of germs, such as putting both their hands and toys in their mouths, facilitating the spread of rotavirus⁶ 

Symptoms

In terms of the symptoms of rotavirus, clinical manifestations of this infection vary based on several different factors including whether the individual is experiencing their first rotavirus infection, or if this is a re-infection, and the age of the individual, as this is an important determinant of disease severity.⁴ Symptoms tend to be more severe during the first infection, with infants presenting more severe symptoms compared to young adults. The incubation period for rotavirus is usually short, varying between 1 to 3 days.⁴ Once incubated, some individuals begin to display common symptoms, which include:

• Fever (a temperature that is 38°C or higher)
• Diarrhoea
• Vomiting 
• Abdominal pain

Babies and younger children have smaller fluid reserves than adults and older children (teenagers), which can cause them to dehydrate much quicker. Loss of too much water from the body (dehydration) occurs due to the large amounts of fluids lost during vomiting and diarrhoea. Therefore, symptoms of dehydration to look out for, especially in babies,⁷ include:

• Sleepiness
• Irritability
• Thirst
• Pale-looking skin
• Lower urine levels

In most cases, recovery of all symptoms takes around 5-7 days, with recovery time varying based on both age and the severity of the infection. 

Symptoms in adults and teenagers

The role of rotavirus in adults and teenagers has long been underappreciated.⁸ Despite rotavirus infections being more common in children, teenagers and adults are also susceptible to rotavirus, contributing to over 45% of the 228,000 diarrhoea deaths occurring in those over the age of 5 and older.⁹ This infection is particularly common in individuals who are immunocompromised, elderly, or those responsible for the care of young children (i.e., nursery workers, parents), with weakened immune systems or increased exposure increasing their susceptibility to becoming infected.⁹ 

Rotavirus in adults and teenagers is spread in the same way as those under 5 years of age, via faecal-oral transmission. In addition to this, the rotavirus symptoms that typically manifest are very similar.⁸ These include:

• Nausea
• Diarrhoea 
• Fever (High temperature)
• Headaches
• Malaise
• Abdominal cramping

However, despite the symptoms mentioned above, it is not uncommon for rotavirus infections to be symptomless in teenagers and adults.⁸ In fact, one of the main differences between the different age groups is the presence of mild symptoms due to more developed immune systems, which aid in reducing the severity of the infection. Additionally, there is the possibility that adults and teenagers have built immunity over time, due to previous exposure to the virus.

Key differences between the different age groups

There are key differences in both the symptoms and the complications that can arise depending on whether the individual is an infant or young child, compared to a teenager or adult. These include:

The intensity and duration of symptoms

Rotavirus symptoms tend to be less severe and shorter in adults, with individuals being asymptomatic in most cases. However, in younger children and infants, symptoms are more severe often requiring treatment or hospitalisation in those under 5 years old.¹⁰

Risk of complications

Those under the age of 5 present smaller fluid reserves, which make them more susceptible to dehydration during rotavirus, as they experience high levels of water loss through vomiting and diarrhoea.⁷ This factor puts these individuals at a higher risk of experiencing severe complications, compared to adults and teenagers.

Immune response and recovery

A faster recovery is often observed in older individuals, compared to infants and younger children, due to these having both quicker and stronger immune systems.

Prevention strategies against rotavirus

There are various ways in which rotavirus infections can be prevented, including:

Hygiene practices

Good hygiene practices help to reduce the spread of rotavirus. This includes washing your hands thoroughly and often, especially after using the toilet or changing nappies. It is also important to keep surfaces clean, sanitising them properly and practising safe food hygiene. 

Vaccination

This is the best way to prevent rotavirus. The rotavirus vaccine helps protect against this infection, it is often given in two separate doses at both 8 and 12 weeks old. Rotavirus vaccines are essential in protecting infants and young children, significantly reducing the severity and duration of the infection, and helping to reduce hospitalizations and mortality in young children.¹¹

Summary

In summary, Rotavirus is a highly contagious gastrointestinal infection causing inflammation in the intestines and the stomach, mainly leading to diarrhoea and vomiting. This virus significantly affects infants and young children, and can also arise in adults and teenagers, despite this occurring less often. While the virus causes symptoms such as diarrhoea, vomiting, and fever in all age groups, young children are more vulnerable to the virus due to underdeveloped immune systems, and lack of prior exposure which makes it harder for them to fight the infection. As well as this, infants and young children present smaller fluid reserves making them prone to dehydration - a serious complication of rotavirus infection. This is because those affected by rotavirus experience a rapid loss of large amounts of fluids. It is this dehydration and severeness of symptoms that younger children experience that often leads to them having to seek treatment or in more severe cases, be hospitalised. In contrast, however, adults and teenagers, when infected by rotavirus, often present milder symptoms or are asymptomatic due to having stronger immune systems and previous exposure, giving them particle immunity. Certain preventative measures can be taken to protect children which include good hygiene and making sure our children get vaccinated with the rotavirus vaccine, which helps to reduce the severity of their symptoms and prevents hospitalisations.